Laser-Assisted Doping and Architecture Engineering of Fe3 O4 Nanoparticles for Highly Enhanced Oxygen Evolution Reaction.

The design and synthesis of cost-effective and highperformance oxygen evolution reaction (OER) electrocatalysts for water splitting based on earth-abundant elements is urgent but challenging. A synergistic doping and architecture engineering strategy by nanosecond laser ablation is used to generate a unique kind of highly disordered Ni-doped Fe3 O4 nanoparticle clusters. Ni dopant and increased oxygen vacancies are simultaneously incorporated into Fe3 O4 frameworks and thereby modulate the electronic configuration for an optimal binding affinity towards OER intermediates. Nanoparticles with average size of around 5 nm assemble randomly during laser ablation and construct a fluffy and porous architecture, which not only optimizes the number of exposed active sites but also accelerates mass transfer. Consequently, Ni-doped Fe3 O4 clusters are revealed as a superior OER catalyst with a small overpotential of 272 mV at 10 mA cm-2 and a small Tafel slope of 39.4 mV dec-1 , surpassing almost all spinel Fe-based OER catalysts. This work provides a new strategy to fabricate advanced cation-doped metal oxide nanostructures for related energy applications.